On 9/16/19 3:25 PM, Laurent Dufour wrote:
Since the commit ba2dd8a26baa ("powerpc/pseries/mm: call H_BLOCK_REMOVE"),
the call to H_BLOCK_REMOVE is always done if the feature is exhibited.
However, the hypervisor may not support all the block size for the hcall
H_BLOCK_REMOVE depending on the segment base page size and actual page
size.
When unsupported block size is used, the hcall H_BLOCK_REMOVE is returning
H_PARAM, which is triggering a BUG_ON check leading to a panic like this:
The PAPR document specifies the TLB Block Invalidate Characteristics which
tells for each couple segment base page size, actual page size, the size of
the block the hcall H_BLOCK_REMOVE is supporting.
Supporting various block sizes doesn't seem needed at that time since all
systems I was able to play with was supporting an 8 addresses block size,
which is the maximum through the hcall, or none at all. Supporting various
size would complexify the algorithm in call_block_remove() so unless this
is required, this is not done.
In the case of block size different from 8, a warning message is displayed
at boot time and that block size will be ignored checking for the
H_BLOCK_REMOVE support.
Due to the minimal amount of hardware showing a limited set of
H_BLOCK_REMOVE supported page size, I don't think there is a need to push
this series to the stable mailing list.
The first patch is reading the characteristic through the hcall
ibm,get-system-parameter and record the supported block size for each page
size. The second patch is changing the check used to detect the
H_BLOCK_REMOVE availability to take care of the base page size and page
size couple.
Changes since V1:
- Remove penc initialisation, this is already done in
mmu_psize_set_default_penc()
- Add details on the TLB Block Invalidate Characteristics's buffer format
- Introduce #define instead of using direct numerical values
- Function reading the characteristics is now directly called from
pSeries_setup_arch()
- The characteristics are now stored in a dedciated table static to lpar.c
you can use
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
for the series.
-aneesh
